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  • Linking macro-, meso- and microscales in multiphase AGN feeding and feedback
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-14
    Massimo Gaspari; Francesco Tombesi; Massimo Cappi
    更新日期:2020-01-15
  • Small in size only
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-14

    Planets and their systems have long held the spotlight, but researchers, space agencies and even the private sector and the public have turned their attention to small bodies.

    更新日期:2020-01-15
  • The first attempts to measure light deflection by the Sun
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-14
    Luís C. B. Crispino; Santiago Paolantonio
    更新日期:2020-01-15
  • Infrared detection of aliphatic organics on a cometary nucleus
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-13
    A. Raponi; M. Ciarniello; F. Capaccioni; V. Mennella; G. Filacchione; V. Vinogradoff; O. Poch; P. Beck; E. Quirico; M. C. De Sanctis; L. V. Moroz; D. Kappel; S. Erard; D. Bockelée-Morvan; A. Longobardo; F. Tosi; E. Palomba; J.-P. Combe; B. Rousseau; G. Arnold; R. W. Carlson; A. Pommerol; C. Pilorget; S. Fornasier; G. Bellucci; A. Barucci; F. Mancarella; M. Formisano; G. Rinaldi; I. Istiqomah; C. Leyrat
    更新日期:2020-01-14
  • A parallax distance to 3C 273 through spectroastrometry and reverberation mapping
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-13
    Jian-Min Wang; Yu-Yang Songsheng; Yan-Rong Li; Pu Du; Zhi-Xiang Zhang
    更新日期:2020-01-14
  • A heatwave of accretion energy traced by masers in the G358-MM1 high-mass protostar
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-13
    R. A. Burns; K. Sugiyama; T. Hirota; Kee-Tae Kim; A. M. Sobolev; B. Stecklum; G. C. MacLeod; Y. Yonekura; M. Olech; G. Orosz; S. P. Ellingsen; L. Hyland; A. Caratti o Garatti; C. Brogan; T. R. Hunter; C. Phillips; S. P. van den Heever; J. Eislöffel; H. Linz; G. Surcis; J. O. Chibueze; W. Baan; B. Kramer
    更新日期:2020-01-14
  • Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-13
    William J. Chaplin; Aldo M. Serenelli; Andrea Miglio; Thierry Morel; J. Ted Mackereth; Fiorenzo Vincenzo; Hans Kjeldsen; Sarbani Basu; Warrick H. Ball; Amalie Stokholm; Kuldeep Verma; Jakob Rørsted Mosumgaard; Victor Silva Aguirre; Anwesh Mazumdar; Pritesh Ranadive; H. M. Antia; Yveline Lebreton; Joel Ong; Thierry Appourchaux; Timothy R. Bedding; Jørgen Christensen-Dalsgaard; Orlagh Creevey; Rafael A. García; Rasmus Handberg; Daniel Huber; Steven D. Kawaler; Mikkel N. Lund; Travis S. Metcalfe; Keivan G. Stassun; Michäel Bazot; Paul G. Beck; Keaton J. Bell; Maria Bergemann; Derek L. Buzasi; Othman Benomar; Diego Bossini; Lisa Bugnet; Tiago L. Campante; Zeynep Çelik Orhan; Enrico Corsaro; Lucía González-Cuesta; Guy R. Davies; Maria Pia Di Mauro; Ricky Egeland; Yvonne P. Elsworth; Patrick Gaulme; Hamed Ghasemi; Zhao Guo; Oliver J. Hall; Amir Hasanzadeh; Saskia Hekker; Rachel Howe; Jon M. Jenkins; Antonio Jiménez; René Kiefer; James S. Kuszlewicz; Thomas Kallinger; David W. Latham; Mia S. Lundkvist; Savita Mathur; Josefina Montalbán; Benoit Mosser; Andres Moya Bedón; Martin Bo Nielsen; Sibel Örtel; Ben M. Rendle; George R. Ricker; Thaíse S. Rodrigues; Ian W. Roxburgh; Hossein Safari; Mathew Schofield; Sara Seager; Barry Smalley; Dennis Stello; Róbert Szabó; Jamie Tayar; Nathalie Themeßl; Alexandra E. L. Thomas; Roland K. Vanderspek; Walter E. van Rossem; Mathieu Vrard; Achim Weiss; Timothy R. White; Joshua N. Winn; Mutlu Yıldız
    更新日期:2020-01-14
  • 更新日期:2020-01-14
  • Linking gravitational waves and X-ray phenomena with joint LISA and Athena observations
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-06
    Sean McGee; Alberto Sesana; Alberto Vecchio
    更新日期:2020-01-06
  • Sensitive probing of exoplanetary oxygen via mid-infrared collisional absorption
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-06
    Thomas J. Fauchez; Geronimo L. Villanueva; Edward W. Schwieterman; Martin Turbet; Giada Arney; Daria Pidhorodetska; Ravi K. Kopparapu; Avi Mandell; Shawn D. Domagal-Goldman
    更新日期:2020-01-06
  • Interactions of type I X-ray bursts with thin accretion disks
    Nat. Astron. (IF 10.500) Pub Date : 2020-01-06
    P. Chris Fragile; David R. Ballantyne; Aidan Blankenship
    更新日期:2020-01-06
  • Big Time
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Paul F. Hoffman

    The Proterozoic Eon was once regarded as the neglected middle half of Earth history. The name refers to early animals, but they did not appear until the eon (2.5–0.54 Ga) was nearly over. Eukaryotic cells and sexual reproduction evolved much earlier in the eon, as did chloroplasts. Molecular dioxygen, the presence of which altered the geochemical behavior of nearly every element essential to life, rose from negligible to near-modern levels, and then plummeted before rising fitfully again. Plate tectonics took on a modern form, and two supercontinents, Nuna and Rodinia, successively congregated and later dispersed. Climate regulatory failures, i.e., Snowball Earth, appear to be a uniquely Proterozoic phenomenon, having occurred twice in rapid succession near the end of the eon (from 717 to 660 Ma and from 650 to 635 Ma) and arguably once near its beginning (ca. 2.43 Ga). Dynamic sea glaciers covered Snowball Earth oceans from pole to pole, and equatorial sublimation drove slow-moving ice sheets on land. Ultimately, the gradual accumulation of CO2 triggered rapid deglaciation and transient greenhouse aftermaths. Physically based and geologically tested, Neoproterozoic Snowball Earth appears to have molecular legacies in ancient bitumens and modern organisms. This is the story of my love affair with an eon that is now a little less neglected.

    更新日期:2019-12-31
  • Unanticipated Uses of the Global Positioning System
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Kristine M. Larson

    Global Positioning System (GPS) instruments are routinely used today to measure crustal deformation signals from tectonic plate motions, faulting, and glacial isostatic adjustment. In parallel with the expansion of GPS networks around the world, several new and unexpected applications of GPS have been developed. For example, GPS instruments are now being used routinely to measure ground motions during large earthquakes. Access to real-time GPS data streams has led to the development of better hazard warnings for tsunamis, flash floods, earthquakes, and volcanic eruptions. Terrestrial water storage changes can be derived from GPS vertical coordinate time series. Finally, GPS signals that reflect on the surfaces below a GPS antenna can be used to measure soil moisture, snow accumulation, vegetation water content, and water levels. In the future, combining GPS with the signals from the Russian, European, and Chinese navigation constellations will significantly enhance these applications. ▪ GPS data are now routinely used to study the dynamics of earthquake rupture. ▪ GPS instruments are an integral part of warning systems for earth- quakes, tsunamis, flash floods, and volcanic eruptions. ▪ Reflected GPS signals provide a new source of soil moisture, snow depth, vegetation water content, and tide gauge data. ▪ GPS networks can sense changes in soil moisture, groundwater, and snow depth and thus can contribute to water resource assessments.

    更新日期:2019-12-31
  • Dynamics in the Uppermost Lower Mantle: Insights into the Deep Mantle Water Cycle Based on the Numerical Modeling of Subducted Slabs and Global-Scale Mantle Dynamics
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Takashi Nakagawa; Tomoeki Nakakuki

    In this review, we address the current status of numerical modeling of the mantle transition zone and uppermost lower mantle, focusing on the hydration mechanism in these areas. The main points are as follows: (a) Slab stagnation and penetration may play significant roles in transporting the water in the whole mantle, and (b) a huge amount of water could be absorbed into the deep mantle to preserve the surface seawater over the geologic timescale. However, for further understanding of water circulation in the deep planetary interior, more mineral physics investigations are required to reveal the mechanism of water absorption in the lower mantle and thermochemical interaction across the core–mantle boundary region, which can provide information on material properties to the geodynamics community. Moreover, future investigations should focus on determining the amount of water in the early planetary interior, as suggested by the planetary formation theory of rocky planets. Moreover, the supplying mechanism of water during planetary formation and its evolution caused by plate tectonics are still essential issues because, in geodynamics modeling, a huge amount of water seems to be required to preserve the surface seawater in the present day and to not be dependent on an initial amount of water in Earth's system. ▪ Slab stagnation and penetration of the hydrous lithosphere are essential for understanding the global-scale material circulation. ▪ Thermal feedback caused by water-dependent viscosity is a main driving mechanism of water absorption in the mantle transition zone and uppermost lower mantle. ▪ The hydrous state in the early rocky planets remains to be determined from cosmo- and geochemistry and planetary formation theory. ▪ Volatile cycles in the deep planetary interior may affect the evolution of the surface environment.

    更新日期:2019-12-31
  • Atmospheric Escape and the Evolution of Close-In Exoplanets
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    James E. Owen

    Exoplanets with substantial hydrogen/helium atmospheres have been discovered in abundance, many residing extremely close to their parent stars. The extreme irradiation levels that these atmospheres experience cause them to undergo hydrodynamic atmospheric escape. Ongoing atmospheric escape has been observed to be occurring in a few nearby exoplanet systems through transit spectroscopy both for hot Jupiters and for lower-mass super-Earths and mini-Neptunes. Detailed hydrodynamic calculations that incorporate radiative transfer and ionization chemistry are now common in one-dimensional models, and multidimensional calculations that incorporate magnetic fields and interactions with the interstellar environment are cutting edge. However, comparison between simulations and observations remains very limited. While hot Jupiters experience atmospheric escape, the mass-loss rates are not high enough to affect their evolution. However, for lower-mass planets, atmospheric escape drives and controls their evolution, sculpting the exoplanet population that we observe today. ▪ Observations of some exoplanets have detected atmospheric escape driven by hydrodynamic outflows, causing the exoplanets to lose mass over time. ▪ Hydrodynamic simulations of atmospheric escape are approaching the sophistication required to compare them directly to observations. ▪ Atmospheric escape sculpts sharp features into the exoplanet population that we can observe today; these features have recently been detected.

    更新日期:2019-12-31
  • The Sedimentary Cycle on Early Mars
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Scott M. McLennan; John P. Grotzinger; Joel A. Hurowitz; Nicholas J. Tosca

    Two decades of intensive research have demonstrated that early Mars (2 Gyr) had an active sedimentary cycle, including well-preserved stratigraphic records, understandable within a source-to-sink framework with remarkable fidelity. This early cycle exhibits first-order similarities to (e.g., facies relationships, groundwater diagenesis, recycling) and first-order differences from (e.g., greater aeolian versus subaqueous processes, basaltic versus granitic provenance, absence of plate tectonics) Earth's record. Mars’ sedimentary record preserves evidence for progressive desiccation and oxidation of the surface over time, but simple models for the nature and evolution of paleoenvironments (e.g., acid Mars, early warm and wet versus late cold and dry) have given way to the view that, similar to Earth, different climate regimes on Mars coexisted on regional scales and evolved on variable timescales, and redox chemistry played a pivotal role. A major accomplishment of Mars exploration has been to demonstrate that surface and subsurface sedimentary environments were both habitable and capable of preserving any biological record. ▪ Mars has an ancient sedimentary rock record with many similarities to but also many differences from Earth's sedimentary rock record. ▪ Mars’ ancient sedimentary cycle shows a general evolution toward more desiccated and oxidized surficial conditions. ▪ Climatic regimes of early Mars were relatively clement but with regional variations leading to different sedimentary mineral assemblages. ▪ Surface and subsurface sedimentary environments on early Mars were habitable and capable of preserving any biological record that may have existed.

    更新日期:2019-12-31
  • New Horizons Observations of the Atmosphere of Pluto
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    G. Randall Gladstone; Leslie A. Young

    New Horizons data provide a snapshot of the current state of Pluto's atmosphere. Winds are slow and mostly controlled by sublimation of surface ices. Molecular nitrogen is the primary constituent below 1,800 km, while methane and carbon monoxide are important minor species. Photolysis of these gases leads to a thin haze that encompasses Pluto from the surface up to >500-km altitude and is important in heating and cooling the atmosphere. A cold (∼70 K) upper atmosphere curtails the escape of Pluto's molecular nitrogen to space, although there is substantial escape of methane (∼5 × 1025 molecules s−1), coincidentally about equal to its loss by photochemistry. It is unknown if the current atmosphere is representative of its long-term average state. From the inferred rapid rate of haze settling, it seems that Pluto's atmosphere must occasionally undergo collapse to allow time for radiation processing of the colorless haze material into the dark deposits found on the surface. ▪ This article outlines what has been gleaned about Pluto's atmosphere in the years since the New Horizons flyby. ▪ Pluto's atmosphere is most similar to Titan's—with the photochemistry of supervolatile nitrogen and hydrocarbons resulting in a kind of factory for cold haze production. ▪ Much has been learned about Pluto's atmosphere, but many new questions have arisen, and these will likely remain unanswered until there is a follow-up mission—no doubt a long time from now.

    更新日期:2019-12-31
  • The Compositional Diversity of Low-Mass Exoplanets
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Daniel Jontof-Hutter

    Low-mass planets have an extraordinarily diverse range of bulk compositions, from primarily rocky worlds to those with deep gaseous atmospheres. As techniques for measuring the masses of exoplanets advance the field toward the regime of rocky planets, from ultrashort orbital periods to Venus-like distances, we identify the bounds on planet compositions, where sizes and incident fluxes inform bulk planet properties. In some cases, the precision of measurement of planet masses and sizes is approaching the theoretical uncertainties in planet models. An emerging picture explains aspects of the diversity of low-mass planets, although some problems remain: Do extreme low-density, low-mass planets challenge models of atmospheric mass loss? Are planet sizes strictly separated by bulk composition? Why do some stellar characterizations differ between observational techniques? With the Transiting Exoplanet Survey Satellite (TESS) mission, low-mass exoplanets around the nearest stars will soon be discovered and characterized with unprecedented precision, permitting more detailed planetary modeling and atmospheric characterization of low-mass exoplanets than ever before. ▪ Following the Kepler mission, studies of exoplanetary compositions have entered the terrestrial regime. ▪ Low-mass planets have an extraordinary range of compositions, from Earth-like mixtures of rock and metal to mostly tenuous gas. ▪ The TESS mission will discover low-mass planets that can be studied in more detail than ever before.

    更新日期:2019-12-31
  • Destruction of the North China Craton in the Mesozoic
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Fu-Yuan Wu; Jin-Hui Yang; Yi-Gang Xu; Simon A. Wilde; Richard J. Walker

    The North China Craton (NCC) was originally formed by the amalgamation of the eastern and western blocks along an orogenic belt at ∼1.9 Ga. After cratonization, the NCC was essentially stable until the Mesozoic, when intense felsic magmatism and related mineralization, deformation, pull-apart basins, and exhumation of the deep crust widely occurred, indicative of destruction or decratonization. Accompanying this destruction was significant removal of the cratonic keel and lithospheric transformation, whereby the thick (∼200 km) and refractory Archean lithosphere mantle was replaced by a thin (<80 km) juvenile one. The decratonization of the NCC was driven by flat slab subduction, followed by a rollback of the paleo-Pacific plate during the late Mesozoic. A global synthesis indicates that cratons are mainly destroyed by oceanic subduction, although mantle plumes might also trigger lithospheric thinning through thermal erosion. Widespread crust-derived felsic magmatism and large-scale ductile deformation can be regarded as petrological and structural indicators of craton destruction. ▪ A craton, a kind of ancient continental block on Earth, was formed mostly in the early Precambrian (>1.8 Ga). ▪ A craton is characterized by a rigid lithospheric root, which provides longevity and stability during its evolutionary history. ▪ Some cratons, such as the North China Craton, can be destroyed by losing their stability, manifested by magmatism, deformation, earthquake, etc.

    更新日期:2019-12-31
  • Seawater Chemistry Through Phanerozoic Time
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Alexandra V. Turchyn; Donald J. DePaolo

    The major ion balance of the ocean, particularly the concentrations of magnesium (Mg), calcium (Ca), and sulfate (SO4), has evolved over the Phanerozoic (last 550 million years) in concert with changes in sea level and the partial pressure of carbon dioxide (pCO2). We review these changes, along with changes in Mg/Ca and strontium/calcium (Sr/Ca) of the ocean; how the changes were reconstructed; and the implication of the suggested changes for the overall charge balance of the ocean. We conclude that marine Mg, Ca, and SO4 concentrations are responding to different aspects of coupled tectonic changes over the Phanerozoic and the resulting effect on sea level. We suggest a broad conceptual model for the Phanerozoic changes in Mg, Ca, and SO4 concentrations along with the seawater 87Sr/86Sr and sulfur isotope composition. ▪ Marine concentrations of magnesium, sulfate, and calcium have varied over the last 550 million years in sync with changes in sea level and atmospheric carbon dioxide. ▪ Seawater chemistry and sea level both respond to supercontinent formation and breakup, age of the ocean floor, and extent of continental shelf area. ▪ Changes in plate tectonics impact the ocean's chemical balance and the carbon cycle in varied ways, resulting in cyclical changes in key climatic variables over geological time.

    更新日期:2019-12-31
  • Global Patterns of Carbon Dioxide Variability from Satellite Observations
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Xun Jiang; Yuk L. Yung

    Advanced satellite technology has been providing unique observations of global carbon dioxide (CO2) concentrations. These observations have revealed important CO2 variability at different timescales and over regional and planetary scales. Satellite CO2 retrievals have revealed that stratospheric sudden warming and the Madden-Julian Oscillation can modulate atmospheric CO2 concentrations in the mid-troposphere. Atmospheric CO2 also demonstrates variability at interannual timescales. In the tropical region, the El Niño–Southern Oscillation and the Tropospheric Biennial Oscillation can change atmospheric CO2 concentrations. At high latitudes, mid-tropospheric CO2 concentrations can be influenced by the Northern Hemispheric annular mode. In addition to modulations by the large-scale circulations, sporadic events such as wildfires, volcanic eruptions, and droughts, which change CO2 surface emissions, can cause atmospheric CO2 concentrations to increase significantly. The natural variability of CO2 summarized in this review can help us better understand its sources and sinks and its redistribution by atmospheric motion. ▪ Global satellite CO2 data offer a unique opportunity to explore CO2 variability in different regions. ▪ Atmospheric CO2 concentration demonstrates variations at intraseasonal, seasonal, and interannual timescales. ▪ Both large-scale circulations and variations of surface emissions can modulate CO2 concentrations in the atmosphere.

    更新日期:2019-12-31
  • Permeability of Clays and Shales
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    C.E. Neuzil

    The low permeability of clays, shales, and other argillaceous lithologies makes them key controls of transport and deformation processes in the crust but is known for being challenging to characterize. As muds are modified by compaction and diagenesis to low-porosity shales, permeability can decrease by six or more orders of magnitude, but at large scales it is often dramatically and unpredictably increased by fractures, faults, and other features. Testing and inverse modeling show that petrophysical properties and the geological environment are dominant controls of clay and shale matrix permeability and its scale dependence. Active sedimentation and tectonism on continental margins cause large-scale permeability to vary with time, but in stable continent interiors it is unclear how regional permeability of argillaceous formations changes over time or, in most cases, what controls it. Although rarely considered, it is also unknown whether Darcian permeability adequately describes flow in clay-rich materials. ▪ Critical for problems in energy, water supply, waste isolation, and geologic hazards, clay and shale permeability remains problematic. ▪ Test data and inverse model analyses are beginning to reveal where and how permeability of clay and shale changes with scale. ▪ In clays and shales, causes of permeability scale effects, their time dependence, and even flow behavior continue to raise questions.

    更新日期:2019-12-31
  • Flood Basalts and Mass Extinctions
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Matthew E. Clapham; Paul R. Renne

    Flood basalts were Earth's largest volcanic episodes that, along with related intrusions, were often emplaced rapidly and coincided with environmental disruption: oceanic anoxic events, hyperthermals, and mass extinction events. Volatile emissions, both from magmatic degassing and vaporized from surrounding rock, triggered short-term cooling and longer-term warming, ocean acidification, and deoxygenation. The magnitude of biological extinction varied considerably, from small events affecting only select groups to the largest extinction of the Phanerozoic, with less-active organisms and those with less-developed respiratory physiology faring especially poorly. The disparate environmental and biological outcomes of different flood basalt events may at first order be explained by variations in the rate of volatile release modulated by longer trends in ocean carbon cycle buffering and the composition of marine ecosystems. Assessing volatile release, environmental change, and biological extinction at finer temporal resolution should be a top priority to refine ancient hyperthermals as analogs for anthropogenic climate change. ▪ Flood basalts, the largest volcanic events in Earth history, triggered dramatic environmental changes on land and in the oceans. ▪ Rapid volcanic carbon emissions led to ocean warming, acidification, and deoxygenation that often caused widespread animal extinctions. ▪ Animal physiology played a key role in survival during flood basalt extinctions, with reef builders such as corals being especially vulnerable. ▪ The rate and duration of volcanic carbon emission controlled the type of environmental disruption and the severity of biological extinction.

    更新日期:2019-12-31
  • Repeating Earthquakes
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Naoki Uchida; Roland Bürgmann

    Repeating earthquakes, or repeaters, are identical in location and geometry but occur at different times. They appear to represent recurring seismic energy release from distinct structures such as slip on a fault patch. Repeaters are most commonly found on creeping plate boundary faults, where seismic patches are loaded by surrounding slow slip, and they can be used to track fault creep at depth. Their hosting environments also include volcanoes, subducted slabs, mining-induced fault structures, glaciers, and landslides. While true repeaters should have identical seismic waveforms, small differences in their seismograms can be used to examine subtle changes in source properties or in material properties of the rocks through which the waves propagate. Source studies have documented the presence of smaller slip patches within the rupture areas of larger repeaters, illuminated earthquake triggering mechanisms, and revealed systematic changes in rupture characteristics as a function of loading rate. ▪ Repeating earthquakes are observed in diverse tectonic and nontectonic settings. ▪ Their occurrence patterns provide quantitative information about fault creep, earthquake cycle dynamics, triggering, and predictability. ▪ Their seismic waveform characteristics provide important insights on earthquake source variability and temporal Earth structure changes.

    更新日期:2019-12-31
  • Soil Functions: Connecting Earth's Critical Zone
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Steven A. Banwart; Nikolaos P. Nikolaidis; Yong-Guan Zhu; Caroline L. Peacock; Donald L. Sparks

    Soil is the central interface of Earth's critical zone—the planetary surface layer extending from unaltered bedrock to the vegetation canopy—and is under intense pressure from human demand for biomass, water, and food resources. Soil functions are flows and transformations of mass, energy, and genetic information that connect soil to the wider critical zone, transmitting the impacts of human activity at the land surface and providing a control point for beneficial human intervention. Soil functions are manifest during bedrock weathering and, in fully developed soil profiles, correlate with the porosity architecture of soil structure and arise from the development of soil aggregates as fundamental ecological units. Advances in knowledge on the mechanistic processes of soil functions, their connection throughout the critical zone, and their quantitative representation in mathematical and computational models define research frontiers that address the major global challenges of critical zone resource provisioning for human benefit. ▪ Connecting the mechanisms of soil functions with critical zone processes defines integrating science to tackle challenges of climate change and food and water supply. ▪ Soil functions, which develop through formation of soil aggregates as fundamental eco-logical units, are manifest at the earliest stages of critical zone evolution. ▪ Global degradation of soil functions during the Anthropocene is reversible through positive human intervention in soil as a central control point in Earth's critical zone. ▪ Measurement and mathematical translation of soil functions and critical zone processes offer new computational approaches for basic and applied geosciences research.

    更新日期:2019-12-31
  • Earthquake Early Warning: Advances, Scientific Challenges, and Societal Needs
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Richard M. Allen; Diego Melgar

    Earthquake early warning (EEW) is the delivery of ground shaking alerts or warnings. It is distinguished from earthquake prediction in that the earthquake has nucleated to provide detectable ground motion when an EEW is issued. Here we review progress in the field in the last 10 years. We begin with EEW users, synthesizing what we now know about who uses EEW and what information they need and can digest. We summarize the approaches to EEW and gather information about currently existing EEW systems implemented in various countries while providing the context and stimulus for their creation and development. We survey important advances in methods, instrumentation, and algorithms that improve the quality and timeliness of EEW alerts. We also discuss the development of new, potentially transformative ideas and methodologies that could change how we provide alerts in the future. ▪ Earthquake early warning (EEW) is the rapid detection and characterization of earthquakes and delivery of an alert so that protective actions can be taken. ▪ EEW systems now provide public alerts in Mexico, Japan, South Korea, and Taiwan and alerts to select user groups in India, Turkey, Romania, and the United States. ▪ EEW methodologies fall into three categories, point source, finite fault, and ground motion models, and we review the advantages of each of these approaches. ▪ The wealth of information about EEW uses and user needs must be employed to focus future developments and improvements in EEW systems.

    更新日期:2019-12-31
  • Noble Gases: A Record of Earth's Evolution and Mantle Dynamics
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Sujoy Mukhopadhyay; Rita Parai

    Noble gases have played a key role in our understanding of the origin of Earth's volatiles, mantle structure, and long-term degassing of the mantle. Here we synthesize new insights into these topics gained from high-precision noble gas data. Our analysis reveals new constraints on the origin of the terrestrial atmosphere, the presence of nebular neon but chondritic krypton and xenon in the mantle, and a memory of multiple giant impacts during accretion. Furthermore, the reservoir supplying primordial noble gases to plumes appears to be distinct from the mid-ocean ridge basalt (MORB) reservoir since at least 4.45 Ga. While differences between the MORB mantle and plume mantle cannot be explained solely by recycling of atmospheric volatiles, injection and incorporation of atmospheric-derived noble gases into both mantle reservoirs occurred over Earth history. In the MORB mantle, the atmospheric-derived noble gases are observed to be heterogeneously distributed, reflecting inefficient mixing even within the vigorously convecting MORB mantle. ▪ Primordial noble gases in the atmosphere were largely derived from planetesimals delivered after the Moon-forming giant impact. ▪ Heterogeneities dating back to Earth's accretion are preserved in the present-day mantle. ▪ Mid-ocean ridge basalts and plume xenon isotopic ratios cannot be related by differential degassing or differential incorporation of recycled atmospheric volatiles. ▪ Differences in mid-ocean ridge basalts and plume radiogenic helium, neon, and argon ratios can be explained through the lens of differential long-term degassing.

    更新日期:2019-12-31
  • Supraglacial Streams and Rivers
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Lincoln H Pitcher; Laurence C. Smith

    Supraglacial meltwater channels that flow on the surfaces of glaciers, ice sheets, and ice shelves connect ice surface climatology with subglacial processes, ice dynamics, and eustatic sea level changes. Their important role in transferring water and heat across and into ice is currently absent from models of surface mass balance and runoff contributions to global sea level rise. Furthermore, relatively little is known about the genesis, evolution, hydrology, hydraulics, and morphology of supraglacial rivers, and a first synthesis and review of published research on these unusual features is lacking. To that end, we review their (a) known geographical distribution; (b) formation, morphology, and sediment transport processes; (c) hydrology and hydraulics; and (d) impact on ice sheet surface energy balance, heat exchange, basal conditions, and ice shelf stability. We conclude with a synthesis of key knowledge gaps and provide recommendations for future research. ▪ Supraglacial streams and rivers transfer water and heat on glaciers, connecting climate with subglacial hydrology, ice sliding, and global sea level. ▪ Ice surface melting may expand under a warming climate, darkening the ice surface and further increasing melt.

    更新日期:2019-12-31
  • Isotopes in the Water Cycle: Regional- to Global-Scale Patterns and Applications
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Gabriel J. Bowen; Zhongyin Cai; Richard P. Fiorella; Annie L. Putman

    Stable isotope ratios of hydrogen and oxygen have been applied to water cycle research for over 60 years. Over the past two decades, however, new data, data compilations, and quantitative methods have supported the application of isotopic data to address large-scale water cycle problems. Recent results have demonstrated the impact of climate variation on atmospheric water cycling, provided constraints on continental- to global-scale land-atmosphere water vapor fluxes, revealed biases in the sources of runoff in hydrological models, and illustrated regional patterns of water use and management by people. In the past decade, global isotopic observations have spurred new debate over the role of soils in the water cycle, with potential to impact both ecological and hydrological theory. Many components of the water cycle remain underrepresented in isotopic databases. Increasing accessibility of analyses and improved platforms for data sharing will refine and grow the breadth of these contributions in the future. ▪ Isotope ratios in water integrate information on hydrological processes over scales from cities to the globe. ▪ Tracing water with isotopes helps reveal the processes that govern variability in the water cycle and may govern future global changes. ▪ Improvements in instrumentation, data sharing, and quantitative analysis have advanced isotopic water cycle science over the past 20 years.

    更新日期:2019-12-31
  • Marsh Processes and Their Response to Climate Change and Sea-Level Rise
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Duncan M. FitzGerald; Zoe Hughes

    In addition to their being vital components of mid- to high-latitude coastal ecosystems, salt marshes contain 0.1% of global sequestered terrestrial carbon. Their sustainability is now threatened by accelerating sea-level rise (SLR) that has reached a rate that is many times greater than the rate at which they formed and evolved. Modeling studies have been instrumental in predicting how marsh systems will respond to greater frequencies and durations of tidal inundation and in quantifying thresholds when marshes will succumb and begin to disintegrate due to accelerating SLR. Over the short term, some researchers believe that biogeomorphic feedbacks will improve marsh survival through greater biomass productivity enhanced by warmer temperatures and higher carbon dioxide concentrations. Increased sedimentation rates are less likely due to lower-than-expected suspended sediment concentrations. The majority of marsh loss today is through wave-induced edge erosion that beneficially adds sediment to the system. Edge erosion is partly offset by upland marsh migration during SLR. ▪ Despite positive biogeomorphic feedbacks, many salt marshes will succumb to accelerating sea-level rise due to insufficient mineral sediment. ▪ The latest multivariate marsh modeling is producing predictions of marsh evolution under various sea-level rise scenarios. ▪ The least well-known variables in projecting changes to salt marshes are suspended sediment concentrations and net sediment influx to the marsh. ▪ We are in the infancy of understanding the importance and processes of marsh edge erosion and the overall dynamicism of marshes. ▪ This review defines the latest breakthroughs in understanding the response of salt marshes to accelerating sea-level rise and decreasing sediment supply. ▪ Climate change is accelerating sea-level rise, warming temperatures, and increasing carbon dioxide, all of which are impacting marsh vegetation and vertical accretion.

    更新日期:2019-12-31
  • The Mesozoic Biogeographic History of Gondwanan Terrestrial Vertebrates: Insights from Madagascar's Fossil Record
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    David W. Krause; Joseph J.W. Sertich; Patrick M. O'Connor; Kristina Curry Rogers; Raymond R. Rogers

    The Mesozoic plate tectonic and paleogeographic history of Gondwana had a profound effect on the distribution of terrestrial vertebrates. As the supercontinent fragmented into a series of large landmasses (South America, Africa-Arabia, Antarctica, Australia, New Zealand, the Indian subcontinent, and Madagascar), particularly during the Late Jurassic and Cretaceous, its terrestrial vertebrates became progressively isolated, evolving into unique faunal assemblages. We focus on four clades that, during the Mesozoic, had relatively low ability for dispersal across oceanic barriers—crocodyliforms, sauropod dinosaurs, nonavian theropod dinosaurs, and mammals. Their distributions reveal patterns that are critically important in evaluating various biogeographic hypotheses, several of which have been informed by recent discoveries from the Late Cretaceous of Madagascar. We also examine the effects of lingering, intermittent connections, or reconnections, of Gondwanan landmasses with Laurasia (through the Caribbean, Mediterranean, and Himalayan regions) on the distributions of different clades. ▪ This article reviews the biogeographic history of terrestrial vertebrates from the Mesozoic of the southern supercontinent Gondwana. ▪ Relatively large, terrestrial animals—including crocodyliforms, sauropod and nonavian theropod dinosaurs, and mammals—are the focus of this review. ▪ Most patterns related to vicariance occurred during the Late Jurassic and Cretaceous, the intervals of most active Gondwanan fragmentation. ▪ Recent discoveries of vertebrates from the Late Cretaceous of Madagascar have played a key role in formulating and testing various biogeographic hypotheses.

    更新日期:2019-12-31
  • Droughts, Wildfires, and Forest Carbon Cycling: A Pantropical Synthesis
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Paulo M. Brando; Lucas Paolucci; Caroline C. Ummenhofer; Elsa M. Ordway; Henrik Hartmann; Megan E. Cattau; Ludmila Rattis; Vincent Medjibe; Michael T. Coe; Jennifer Balch

    Tropical woody plants store ∼230 petagrams of carbon (PgC) in their aboveground living biomass. This review suggests that these stocks are currently growing in primary forests at rates that have decreased in recent decades. Droughts are an important mechanism in reducing forest C uptake and stocks by decreasing photosynthesis, elevating tree mortality, increasing autotrophic respiration, and promoting wildfires. Tropical forests were a C source to the atmosphere during the 2015–2016 El Niño–related drought, with some estimates suggesting that up to 2.3 PgC were released. With continued climate change, the intensity and frequency of droughts and fires will likely increase. It is unclear at what point the impacts of severe, repeated disturbances by drought and fires could exceed tropical forests’ capacity to recover. Although specific threshold conditions beyond which ecosystem properties could lead to alternative stable states are largely unknown, the growing body of scientific evidence points to such threshold conditions becoming more likely as climate and land use change across the tropics. ▪ Droughts have reduced forest carbon uptake and stocks by elevating tree mortality, increasing autotrophic respiration, and promoting wildfires. ▪ Threshold conditions beyond which tropical forests are pushed into alternative stable states are becoming more likely as effects of droughts intensify.

    更新日期:2019-12-31
  • Exoplanet Clouds
    Annu. Rev. Earth Planet. Sci. (IF 9.235) Pub Date : 2019-05-30
    Christiane Helling

    Clouds, which are common features in Earth's atmosphere, form in atmospheres of planets that orbit other stars than our Sun, in so-called extrasolar planets or exoplanets. Exoplanet atmospheres can be chemically extremely rich. Exoplanet clouds are therefore composed of a mix of materials that changes throughout the atmosphere. They affect atmospheres through element depletion and through absorption and scattering; hence, they have a profound impact on an atmosphere's energy budget. While astronomical observations point us to the presence of extrasolar clouds and make first suggestions on particle size and material composition, we require fundamental and complex modeling work to merge the individual observations into a coherent picture. Part of this work includes developing an understanding of cloud formation in nonterrestrial environments. ▪ Exoplanet atmospheres exhibit a wide chemical diversity that enables the formation of mineral clouds in contrast to the predominant water clouds on Earth. ▪ Clouds consume elements, causing specific atoms and molecules to drop in abundance. Transport processes such as gravitational settling or advection delocalize this process. ▪ Extrasolar planets can have extreme weather conditions where day- and nightside temperatures vary hugely. This affects cloud formation, and hence the cloud coverage and atmosphere's appearance can change dramatically. ▪ Dynamic extrasolar clouds develop intracloud lightning, and electric circuits may occur on more local, smaller scales in giant exoplanets compared to smaller, Earth-like planets with less dramatic hydrodynamics.

    更新日期:2019-12-31
  • An ablating 2.6 M ⊕ planet in an eccentric binary from the Dispersed Matter Planet Project
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-23
    John R. Barnes; Carole A. Haswell; Daniel Staab; Guillem Anglada-Escudé; Luca Fossati; James P. J. Doherty; Joseph Cooper; James S. Jenkins; Matías R. Díaz; Maritza G. Soto; Pablo A. Peña Rojas
    更新日期:2019-12-23
  • Coevolution of Mars’s atmosphere and massive south polar CO 2 ice deposit
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-23
    P. B. Buhler; A. P. Ingersoll; S. Piqueux; B. L. Ehlmann; P. O. Hayne
    更新日期:2019-12-23
  • Dispersed Matter Planet Project discoveries of ablating planets orbiting nearby bright stars
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-23
    Carole A. Haswell; Daniel Staab; John R. Barnes; Guillem Anglada-Escudé; Luca Fossati; James S. Jenkins; Andrew J. Norton; James P. J. Doherty; Joseph Cooper
    更新日期:2019-12-23
  • A compact multi-planet system around a bright nearby star from the Dispersed Matter Planet Project
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-23
    D. Staab; C. A. Haswell; J. R. Barnes; G. Anglada-Escudé; L. Fossati; J. P. J. Doherty; J. Cooper; J. S. Jenkins; M. R. Díaz; M. G. Soto
    更新日期:2019-12-23
  • A bridge between research, education and communication
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-19
    F. Chiappetta; F. Pecora; G. Prete; A. Settino; V. Carbone; P. Riccardi
    更新日期:2019-12-19
  • Early formation and recent starburst activity in the nuclear disk of the Milky Way
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-16
    Francisco Nogueras-Lara; Rainer Schödel; Aurelia Teresa Gallego-Calvente; Eulalia Gallego-Cano; Banafsheh Shahzamanian; Hui Dong; Nadine Neumayer; Michael Hilker; Francisco Najarro; Shogo Nishiyama; Anja Feldmeier-Krause; Julien H. V. Girard; Santi Cassisi
    更新日期:2019-12-17
  • Our Galaxy’s second growth spurt
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-16
    Davide Massari
    更新日期:2019-12-17
  • Sub one per cent mass fractions of young stars in red massive galaxies
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-16
    Núria Salvador-Rusiñol; Alexandre Vazdekis; Francesco La Barbera; Michael A. Beasley; Ignacio Ferreras; Andrea Negri; Claudio Dalla Vecchia
    更新日期:2019-12-17
  • The great isotopic dichotomy of the early Solar System
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-16
    Thomas S. Kruijer; Thorsten Kleine; Lars E. Borg
    更新日期:2019-12-17
  • One halo mass to rule them all
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-12
    Marios Karouzos
    更新日期:2019-12-13
  • Exploring the innermost solar atmosphere
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Eugene N. Parker

    The Parker Solar Probe spacecraft completed the first two of its 24 scheduled orbits around the Sun on 18 June 2019, making history by flying halfway between Mercury and the Sun.

    更新日期:2019-12-11
  • A comparison of inner Solar System volcanism
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Paul K. Byrne
    更新日期:2019-12-11
  • Titan’s climate patterns and surface methane distribution due to the coupling of land hydrology and atmosphere
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Sean P. Faulk, Juan M. Lora, Jonathan L. Mitchell, P. C. D. Milly
    更新日期:2019-12-11
  • Constraining black hole–galaxy scaling relations and radiative efficiency from galaxy clustering
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Francesco Shankar, Viola Allevato, Mariangela Bernardi, Christopher Marsden, Andrea Lapi, Nicola Menci, Philip J. Grylls, Mirko Krumpe, Lorenzo Zanisi, Federica Ricci, Fabio La Franca, Ranieri D. Baldi, Jorge Moreno, Ravi K. Sheth
    更新日期:2019-12-11
  • The origin of s -process isotope heterogeneity in the solar protoplanetary disk
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Mattias Ek, Alison C. Hunt, Maria Lugaro, Maria Schönbächler
    更新日期:2019-12-11
  • Cascading parallel fractures on Enceladus
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-09
    Douglas J. Hemingway, Maxwell L. Rudolph, Michael Manga
    更新日期:2019-12-11
  • The multi-scale nature of the solar wind
    Living Rev. Sol. Phys. (IF 14.625) Pub Date : 2019-12-09
    Daniel Verscharen, Kristopher G. Klein, Bennett A. Maruca

    The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions, waves, turbulence, and kinetic microinstabilities for the multi-scale plasma evolution.

    更新日期:2019-12-09
  • Assessing the influence of one astronomy camp over 50 years
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Hannah S. Dalgleish, Joshua L. Veitch-Michaelis
    更新日期:2019-12-07
  • Diversity and inclusion in Australian astronomy
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Lisa J. Kewley
    更新日期:2019-12-07
  • Actions speak louder than words
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06

    Diversity of thought and perspective fosters innovation and productivity. Equity is an ethical imperative. There is plenty of scope to improve both diversity and equity in our field and this issue’s Focus puts the spotlight on actions today for a more inclusive tomorrow.

    更新日期:2019-12-07
  • 更新日期:2019-12-07
  • Astronomy networks and best practices for inclusion in Japan
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Kumiko Usuda-Sato, Shin Mineshige, Lina Canas
    更新日期:2019-12-07
  • Why I teach growth mindset
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Adam J. Burgasser
    更新日期:2019-12-07
  • 更新日期:2019-12-07
  • The multi-colour dynamic Universe explored
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Paul J. Groot
    更新日期:2019-12-07
  • PhD bridge programmes as engines for access, diversity and inclusion
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Alexander L. Rudolph, Kelly Holley-Bockelmann, Julie Posselt
    更新日期:2019-12-07
  • De-biasing the evaluation process of in-person review panels for a postdoctoral fellowship
    Nat. Astron. (IF 10.500) Pub Date : 2019-12-06
    Joyce W. Yen

    Good intentions are not enough to advance diversity. This case study of a 2019 postdoctoral fellowship competition in astronomy illustrates how incorporating lessons from social science research into the evaluation process mitigates bias, identifies outstanding scientists, and improves diversity.

    更新日期:2019-12-07
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